Should we stop eating shellfish?

As ocean temps rise, so may a toxin found in these edible creatures.

Something harmful may be lurking in this dish of mussels and spaghetti if ocean temperatures continue to rise.
(Photo: Joerg Beuge/shutterstock)

Among the things climate change is altering, add future clam bakes to the list. Scientists are warning that as our ocean temperatures rise, our shellfish may become more toxic, according to Live Science. They reached this conclusion after looking at 20 years of data examining ocean water off the Oregon coast and the levels of a toxin in Oregon's razor clams.

The study showed that during the five years the ocean waters were the warmest, the toxin domoic acid was at its highest levels. Domoic acid is produced by algae, and it builds up in shellfish, sardines and anchovies, according to The Marine Mammal Center. Exposure to this biotoxin can affect the brain and cause other sea creatures or humans who ingest the toxic seafood to become ill. Possible effects of domoic acid poisoning (DAP) include lethargy, disorientation, stomach pains, diarrhea, seizures and even death in rare cases.

Cooking or freezing the shellfish does not lower the amount of domoic acid according to Live Science, which reports the toxin wasn't identified as a health threat until 1987. Since then, agencies have monitored domoic acid levels in shellfish every few weeks. Harvesting is suspended if the level of the toxin exceeds 20 parts per million in shellfish tissue.

Such was the case last fall when certain portions of Maine's coastline were closed to shellfish harvesting, according to Food Safety News. Domoic acid was present in dangerously high levels, and in addition to harvesting being shut down, clams and mussels that had already been harvested were recalled.

Halting harvesting of shellfish because of dangerously high domoic acid levels is not as common on the East Coast as it is on the West Coast. Whether the uncommonly dangerous East Coast domoic acid levels were due to climate change or an anomaly is unknown.

For now, the situation is still a wait and see one, but Matthew Hunter, one of the study's researchers from Oregon State University told Live Science "the biggest takeaway is that the ocean temperatures are changing, and that has the potential for more frequent and more extreme harmful algal blooms." Those algal blooms could have big implications for fisheries, seafood, and the humans who consume the seafood.